namespace MLAgents.RewardProvider
{
    /// <summary>
    /// Reward providers allow users to provide rewards for Agent behavior during training in order to
    /// give hints on what types of actions are "better" than others based on an Agent's previous observation.
    /// </summary>
    public interface IRewardProvider
    {
        /// <summary>
        /// Get an incremental reward to pass along to a trainer.  
        /// </summary>
        /// <returns></returns>
        float GetIncrementalReward();

        /// <summary>
        /// This function is called on every step of the simulation and should be
        /// used as a place to store an <see cref="Agent"/>'s incremental reward
        /// before the reward is sent off to the brain from the
        /// <see cref="GetIncrementalReward"/> method.
        /// </summary>
        void RewardStep();

        /// <summary>
        /// Notifies the RewardProvider that the current reward should be reset.  If done is false,
        /// the incremental reward should only be reset, otherwise both the incremental and cumulative
        /// reward should be reset.
        /// <param name="done">Flag indicating whether the Agent episode is done or not.</param>
        /// </summary>
        void ResetReward(bool done=false);
    }
}